Decorators are used to add extra functionality onto existing methods. They act as an extra steps either before or after the method call. It essentially allows you to modify the inputs or outputs before they are passed into the method or after they come out of the method respectively.
def square(fn):
def wrapper(*args, **kwargs):
result = fn(*args, **kwargs)
return result*result
return wrapper
@square
def add(x, y):
return x + y
print(add(2, 2)) # 16
def header(string):
def decorate(fn):
def wrapper(*args, **kwargs):
result = fn(*args, **kwargs)
return string + str(result*result)
return wrapper
return decorate
@header("Answer: ")
def subtract(x, y):
return x - y
print(subtract(10, 4)) # Answer: 36
class Header:
def __init__(self, string):
self.string = string
def __call__(self, fn):
def wrapper(*args, **kwargs):
result = fn(*args, **kwargs)
return self.string + str(result)
return wrapper
@Header("Result: " )
def divide(x, y):
return x/y
print(divide(10, 2)) # Result: 5.0
divide_header = Header("Answer: ")(divide)
print(divide_header(12, 2)) # Answer: 6.0